'Use crossfading backend' fixed this BUT can't play m4a files when crossfading backend is enabled ( https://bugs.launchpad.net/ubuntu/+source/rhythmbox/+bug/138728 )
'Use crossfading backend' fixed this BUT can't play m4a files when crossfading backend is enabled ( https:/ /bugs.launchpad .net/ubuntu/ +source/ rhythmbox/ +bug/138728 )